The production of copper typically involves a multi-step procedure which includes concentration, smelting, converting, refining, anode casting and electrolytic refining procedures. Typically, starting with an ore comprising one or more of a copper sulfide or copper-iron-sulfide mineral, such as chalcocite, chalcopyrite and bornite, the ore is converted to a concentrate containing usually between 25 and 35 weight percent (wt %) copper. The concentrate is then converted with heat and oxygen first to a matte and then to blister copper. Additional solid copper scrap is often added to the blister copper. The further refining of the blister copper accomplishes the reduction of oxygen and sulfur impurities in the blister copper, typically from levels as high as 0.80% and 1.0%, respectively, to levels as low as 0.05% and 0.002%, respectively and is usually carried out in the temperature range of about 1090° C. (2000° F.) to 1300° C. (2400° F.) and includes an oxidation process to oxidize sulfur to sulfur dioxide which desolubilizes out of the bath as well as a reduction process to remove dissolved oxygen present after the oxidation step.
The refining of the blister copper to anode copper may be conducted as a batch process or semi-continuous process. In either case, high velocity submerged tuyeres are typically used for the injection of the oxidant gas and reductant gas streams into the copper melt. However, numerous operational difficulties and significant costs are associated with conventional copper anode fire refining process and injection of the oxidant and reductant gas streams via submerged tuyeres. Such difficulties include: tuyere maintenance and reliability concerns; high furnace refractory wear due to the corrosive effects of the oxidant and reducing gases; excessive NOx formation, and refining process variations.
What is needed is an improved copper anode refining method that eliminates the need for submerged tuyeres and which achieves high refining efficiencies and throughput while at the same lowering operational costs and achieving reductions in the levels of NOx associated with copper anode refining process.
The presently disclosed system and method of copper refining with coherent gas streams includes multiple features and aspects that alone and collectively enhance the copper refining process from a productivity and environmental standpoint. These inventive aspects and features are presented in more detail in the sections that follow.